Altered natural killer cell activity in childhood acute non-lymphoid leukaemia. Augmented natural killer cell activity and cells expressing the Leu 7 and Leu 11b (CD 16) markers in the bone marrow of children in remission.

Peripheral blood and bone marrow mononuclear cells from 25 children with acute non-lymphoid leukaemia were analysed for natural killer cell activity and for cells with the Leu-7 and Leu-11b (CD 16) markers. Significantly reduced spontaneous cytotoxicity was detected in peripheral blood from children with untreated and active acute non-lymphoid leukaemia compared with that of the controls (P = 0.01 and P less than 0.05). Patients in remission, however, had normal natural cytotoxicity and normal numbers of Leu-7 and Leu-11b (CD 16)-positive cells. The natural killer cell activity in bone marrow from patients with untreated acute non-lymphoid leukaemia was also significantly reduced (P = 0.025). On the other hand, patients in remission had both an increased percentage of Leu-7 and Leu-11b (CD 16)-positive cells (P less than 0.05) and an increased natural killer cell activity (P less than 0.0005) in their bone marrow cells in comparison with the control group. This augmented natural killer cell activity is most probably a result of anti-leukaemic treatment. Stimulation with recombinant alpha interferon and recombinant interleukin 2 caused an increase in natural killer cell activity that was both significant and normal in both peripheral blood and bone marrow from children with acute non-lymphoid leukaemia.